International veterinary canine dyskinesia task force ECVN consensus statement: Terminology and classification

Development of a Novel Epilepsy and Dyskinesia Survey for Large-Scale Characterization of Seizure Semiology in Dogs

BACKGROUND

Diagnosing epilepsy and dyskinesia in dogs relies on seizure semiology, laboratory workup, brain imaging, and electroencephalography. Variability in existing epilepsy surveys complicates comparison and impedes epidemiologic and genetic research.

OBJECTIVE

To characterize the semiology of epileptic seizures and dyskinesia episodes using a novel, owner-completed, multi-language online questionnaire.

ANIMALS

A cohort of 606 dogs from 96 breeds with paroxysmal events, perceived by their owners as epilepsy or dyskinesia.

MATERIALS AND METHODS

A comprehensive epilepsy and dyskinesia questionnaire featuring pragmatic seizure categories and video upload was developed in German, Finnish, and English. The reliability of the questionnaire was assessed, and the study cohort analyzed.

RESULTS

The questionnaire demonstrated strong internal consistency and interrater agreement. Owners correctly classified paroxysmal events in 90.1% of cases (95% CI 88.18-92.11). Video footage was submitted from 23.8% (143/606) and supported the seizure type in the questionnaire in 96.5%. The age of onset ranged from 6 months to 6 years in 80.2% (median 2 years; IQR 1-5 years). Generalized (epileptic) convulsive seizures occurred in 58.6% of dogs, non-generalized paroxysmal motor events without convulsions in 58.1%, sudden falls without movement in 6.1%, episodes of impaired awareness in 15.8%, and other unclassified events in 7.1%. Multiple seizure types were reported in 25.2% of the dogs. Labrador Retrievers exhibited a higher prevalence of non-generalized motor events compared to Border Collies, Siberian Huskies, and other breeds (p < 0.001).

CONCLUSIONS

The questionnaire reliably characterizes epileptic seizures and dyskinesia episodes in dogs, making it a valuable tool for large-scale epidemiological and genetic studies.

Facial Myokymia With or Without Concurrent Neurological Deficits in Seven Dogs and Two Cats

BACKGROUND

Myokymia is a form of peripheral nerve hyperexcitability that can be focal or generalized. Information regarding focal myokymia in veterinary medicine is currently limited, resulting in a need for a better understanding of this clinical sign.

HYPOTHESIS/OBJECTIVES

Describe the clinical presentation, diagnostic findings, treatment, and outcomes in dogs and cats with facial myokymia (FM).

ANIMALS

Seven dogs and two cats with clinically confirmed FM.

METHODS

Retrospective study. Clinical records from six referral institutions were reviewed to identify cases with FM. Signalment, clinical presentation, diagnostic test results, treatment, and outcome were recorded and evaluated for each patient.

RESULTS

Facial myokymia was detected before referral in 6/9 cases. Concurrent vestibular signs were present in 7/9 cases, whereas signs of facial nerve dysfunction other than FM were present in three cases. The diagnoses in the seven dogs were facial and vestibular neuropathy of unknown etiology (n = 2), extra-axial neoplasia (n = 1), otitis media-interna with intracranial extension (n = 1), otitis interna with associated facial and vestibulocochlear neuropathy (n = 1), meningoencephalitis of unknown origin (n = 1) and neoplasia or hypertrophic neuritis (n = 1). The two cats were diagnosed with retrobulbar adenosquamous carcinoma with intracranial extension and traumatic orofacial injury. When prednisolone was used (6/9 cases) FM improved or resolved, although relapses were common.

CONCLUSIONS AND CLINICAL IMPORTANCE

Facial myokymia is an uncommon and nonspecific clinical sign in dogs and cats, associated with a range of structural disorders affecting the facial motor nucleus, nerve, or both. Control of FM is variable, and treatment and outcome depend on the underlying cause.

Tremors in cats: 105 cases (2004-2023)

Although tremors are common neurological presentations, there is little known about their clinical features and underlying etiologies in cats. The aim of this study was to evaluate the clinical features, and underlying diagnoses in cats with tremors. We hypothesized that the results of this study would provide clinically useful information for clinicians when evaluating cats with tremors. This is a retrospective, single-center, study of cats with tremors between 2004 and 2023. Inclusion criteria included complete medical records, presence or report of tremor or twitch, and a final or presumptive diagnosis. One hundred five cats met the inclusion criteria. The most common diagnoses associated with tremors were degenerative encephalopathy (19/105; 18.1 %), feline infectious peritonitis (FIP) (17/105; 16.2 %), congenital portosystemic shunt (17/105; 16.2 %), intoxication (16/105 15.2 %) and polyneuropathy (8/105; 7.6 %). Most common degenerative encephalopathies were suspected cerebellar cortical degeneration (7/19; 50 %) and lysosomal storage diseases (7/19; 50 %) and manifested intention head tremors. Intention head tremors were also seen in cats with FIP and thiamine deficiency encephalopathy. Portosystemic shunt tremors were of variable features, focal or generalised, intentional, nonintentional or both. The most common intoxication was permethrin ingestion and was most commonly associated with generalized tremors as the main presenting complaint. The most common type of tremor in cats with a polyneuropathy was a generalised tremor or limb tremor. Different tremor phenotypes occur and are associated with specific underlying diagnoses in cats. This information can aid clinicians on the best way to approach cats with a variety of tremor phenotypes.

High-field MRI findings in epileptic dogs with a normal inter-ictal neurological examination

Introduction

Epilepsy is one of the most common chronic neurological conditions affecting dogs. Previous research exploring the likelihood of a structural cause of epilepsy specifically in dogs with a normal inter-ictal examination is limited to a small population of dogs using low-field MRI. The aims of this study were to establish high-field (1.0T and 1.5T) MRI findings in dogs presenting with epileptic seizures and a normal inter-ictal examination.

Methods

Medical records were retrospectively searched for dogs presenting with at least two epileptic seizure events more than 24 h apart. To be included in the study, patients had to have a normal neurological examination, high-field MRI of the brain and have had metabolic and toxic causes excluded.

Results

Four hundred and twelve dogs were eligible for inclusion. Crossbreeds were most commonly affected (n = 63, 15.3%) followed by Border collies (n = 39, 9.5%) and Labrador retrievers (n = 26, 6.3%). Seventy-six dogs (18.5%) had abnormalities detected on MRI, 60 (78.9%) of which were considered to be incidental. Overall, 16 dogs (3.9%) had a structural cause of their epileptic seizures including neoplasia (n = 13, 81.3%), anomalous (n = 2, 12.5%) and meningoencephalitis of unknown origin (MUO) (n = 1, 6.3%). When split into age group at first epileptic seizure structural lesions were documented in 0/66 dogs aged <1 year, 4/256 (1.6%) dogs aged ≥1 year ≤6 years (three neoplastic and one anomalous), 3/51 (5.9%) aged >6 years ≤8 years (two neoplastic and one MUO), and 9/39 (23.1%) dogs aged >8 years (eight neoplastic, one anomalous). Multivariate analysis identified two risk factors for structural disease: increasing age at first epileptic seizure (p < 0.001, OR = 4.390, CI 2.338-8.072) and a history of status epilepticus (p = 0.049, OR = 4.389, CI 1.010-19.078).

Discussion

Structural lesions are an uncommon cause of epilepsy at any age in dogs with a normal inter-ictal examination.

Clinical characterization of a novel episodic ataxia in young working Cocker Spaniels

BACKGROUND

Episodic ataxias (EAs) are a rare group of paroxysmal movement disorders (PMD) described in human medicine with only one suspected case described in veterinary literature.

HYPOTHESIS/OBJECTIVES

This study aimed to provide clinical description of a suspected primary EA in working Cocker Spaniel (WCS) dogs.

ANIMALS

Seven WCS dogs with suspected primary EA.

METHODS

Descriptive, retrospecitve, multicenter study. Clinical signs, video footage, investigations, treatment, and outcome were reviewed. Owners of affected dogs were invited to complete a questionnaire.

RESULTS

The mean age at clinical onset was 4 months. Signs were acute and included episodic body swaying, titubation, cerebellar ataxia, wide-base stance, and hypermetria, all while mentation remained unaltered. Neither autonomic nor vestibular signs nor hyperkinetic movements were observed. Duration of episodes ranged from 30 minutes up to 24 hours, and their frequency varied from weekly to once every 5 months. When investigations were performed, results revealed no abnormalities except for 1 dog that had increased gluten antibody titers. None of the dogs deteriorated, and in dogs with available follow-up (5/7) the frequency of episodes decreased or completely resolved, from which the majority (4/5) received gluten-free diet.

CONCLUSION AND CLINICAL IMPORTANCE

A novel PMD was identified in young WCS, manifesting as EA. The condition is suspected to have a primary (genetic) etiology, although the cause of this manifestation has not yet been identified. Episodic ataxia in our WCS had a good prognosis. Veterinarians must be aware of this presentation, and further investigations are needed to determine the origin of the clinical signs.

Case series: Cervical far-lateral and combined cervical far lateral/foraminal intervertebral disk extrusions in 10 dogs

Far-lateral intervertebral disk extrusions (IVDEs) have been reported infrequently in dogs in veterinary literature, mostly affecting the caudal lumbar intervertebral disks. We describe the clinical findings, computed tomography (CT) and magnetic resonance imaging (MRI) findings, treatment, and outcome in 10 dogs with cervical far-lateral IVDEs. Patient databases of 3 small animal hospitals and 1 veterinary teleradiology service were retrospectively searched for patients in which imaging studies (CT or MRI) identified the presence of intervertebral disk material outside the limits of the intervertebral foramen. Presenting clinical signs included: episodic signs of cervical pain (6/10, 30%), persistent signs of cervical pain (3/10, 50%), nerve root signature or lameness (5/10, 50%), and abnormal cervical posture only (excluding nerve root signature) (1/10, 10%). Affected IVD spaces (for 11 IVDEs in 10 dogs) included: C3-4 (6/11, 55%), C5-6 (3/11, 27%), and C2-3 (2/11, 18%). Nerve root signature was not reported for C2-3 IVDEs. All cases were managed medically (without surgery). The top 3 used medications were gabapentinoids (10/10, 100%), non-steroidal anti-inflammatory drugs (NSAIDs) (10/10, 100%), and paracetamol (3/10, 30%). Median treatment duration was 25 days (range 10-84). Short-term outcome (<3 months) was recorded in 9/10 (90%) cases. Resolution of clinical signs was reported in 7/9 (78%) cases. Long-term follow-up was available for 6/10 (60%) cases (median 11.5 months, range 5.5-30 months); 5/6 (83%) showed resolution of clinical signs. Recurrence of clinical signs was reported in 1 case (9 months later), managed medically again, with successful outcome. In conclusion, cervical far-lateral disk extrusions are a rare clinical entity in dogs, but can result in severe, persistent or episodic, pain. Medical management is associated with a positive short- and long-term outcome in most cases.

Cushing's Myopathy in Dogs: Prevalence, Clinical Abnormalities, and Response to Treatment

A distinct myotonia is a muscle disorder that may occur secondary to excess corticosteroids (hyperadrenocorticism, HAC, or Cushing's disease) and is associated with electrodiagnostic abnormalities on electromyography (EMG). Clinically these disorders cause muscle stiffness, weakness, atrophy, and/or contractures, which can severely limit the quality of life of those affected. To date, there are very few published data regarding the onset, development, and treatment of hyperadrenocorticism-associated myotonia/pseudomyotonia. This is a multi-institutional retrospective study describing the clinical signs, diagnosis, and treatment of HAC-associated myotonia/pseudomyotonia. We found that this disorder was and continues to be rare. It most commonly occurs in adult dogs with chronic steroid exposure secondary to pituitary-dependent HAC. No cases of adrenal dependent HAC were identified in this population. In addition to muscle stiffness, dermatologic disease and liver enzyme abnormalities were common. A wide variety of therapeutic strategies, including polypharmacy and physical rehabilitation, were implemented, with little success. Analgesics were the most frequently administered type of medication.

Suspected paroxysmal dyskinesia in four small-breed dogs: Clinical presentation, diagnosis, management and prognosis

This case report details the clinical presentation, diagnosis, management and prognosis of paroxysmal dyskinesia (PD) in four small-breed dogs, each weighing under 6 kg: A 7-year-old spayed female Pomeranian, an 8-year-old female mixed breed, a 1-year-old female Pomeranian and a 9-year-old castrated male Poodle. These dogs were referred to our hospital due to movement disorders. Diagnosis was facilitated by video recordings of the episodes, assessing motor activity, consciousness, episode duration, any pre- or post-episodic behaviour as well as the presence of autonomic signs. Magnetic resonance imaging conducted on two of the dogs returned unremarkable results. Treatment trials included a gluten-free diet for all four dogs, with two also receiving acetazolamide. This intervention led to a decrease in the frequency of abnormal movement in all patients. Our findings suggest that PD in dogs can be effectively diagnosed through detailed symptom description using videos and questionnaires. Furthermore, once diagnosed, a combination of nutritional and medical management can be beneficial.

Canine paroxysmal dyskinesia-a review

Paroxysmal dyskinesias (PDs) are a group of involuntary, hyperkinetic movement disorders that recur episodically and may last seconds to hours. An important feature of PD is that there is no loss of consciousness during the episode. Using a clinical classification, three main types of PDs have been distinguished in canine PD: (1) paroxysmal kinesigenic dyskinesia (PKD) that commences after (sudden) movements, (2) paroxysmal non-kinesigenic dyskinesia (PNKD) not associated with exercise and can occur at rest, and (3) paroxysmal exertion-induced dyskinesia (PED) associated with fatigue. Canine PDs are diagnosed based on the clinical presentation, history, and phenomenology. For the latter, a video recording of the paroxysmal event is extremely useful. An etiological classification of canine PDs includes genetic (proven and suspected), reactive (drug-induced, toxic, metabolic, and dietary), structural (neoplasia, inflammatory, and other structural causes), and unknown causes. In this review, an overview of all reported canine PDs is provided with emphasis on phenotype, genotype, and, where possible, pathophysiology and treatment for each reported canine PD.

Emergency Approach to Acute Seizures in Dogs and Cats

Seizures are a common presentation seen in small animal practices. Seizures require prompt management including initial interventions for triage, stabilization, and treatment with first-line anticonvulsant (AC) drugs like benzodiazepines. Concurrently, ruling out metabolic or extracranial causes with point-of-care diagnostics can help guide further diagnostics and treatments. Analysis of the history and a physical exam are also necessary to rule out common "look-alikes" that require specific diagnostic workup and treatments. Typically, causes of seizures can be grouped into intracranial and extracranial causes, with the latter being easier to diagnose with commonly available tests. This review presents a systematic approach to the diagnosis and treatment of single seizures, cluster seizures, and status epilepticus in dogs and cats.

The Spontaneous Incidence of Neurological Clinical Signs in Preclinical Species Using Cage-side Observations or High-definition Video Monitoring: A Retrospective Analysis

When conducting toxicology studies, the interpretation of drug-related neurological clinical signs such as convulsions, myoclonus/myoclonic jerks, tremors, ataxia, and salivation requires an understanding of the spontaneous incidence of those observations in commonly used laboratory animal species. The spontaneous incidence of central nervous system clinical signs in control animals from a single facility using cage-side observations or high definition video monitoring was retrospectively analyzed. Spontaneous convulsions were observed at low incidence in Beagle dogs and Sprague-Dawley rats but were not identified in cynomolgus monkeys and Göttingen minipigs. Spontaneous myoclonic jerks and muscle twitches were observed at low incidence in Beagle dogs, cynomolgus monkeys, and Sprague-Dawley rats but were not seen in Göttingen minipigs. Spontaneous ataxia/incoordination was identified in all species and generally with a higher incidence when using video monitoring. Salivation and tremors were the two most frequent spontaneous clinical signs and both were observed in all species. Data from the current study unveil potential limitations when using control data obtained from a single study for toxicology interpretation related to low incidence neurological clinical signs while providing historical control data from Beagle dogs, cynomolgus monkeys, Sprague-Dawley rats, and Göttingen minipigs.

Polioencephalopathy in Eurasier dogs

BACKGROUND

Polioencephalopathies secondary to inborn errors of metabolism have been described in dogs, but few genetically characterized.

OBJECTIVES

Clinically and genetically characterize polioencephalopathy in a family of Eurasier dogs.

ANIMALS

Three Eurasier dogs (littermates) presented with early onset movement disorders (9 weeks in 2, 4-6 months in 1). Progressive gait abnormalities were detected in 2 of the dogs, persistent divergent strabismus in 1, whereas consciousness and behavior remained intact in all dogs. One dog was euthanized at 25 months.

METHODS

Video footage was assessed in all dogs, and Dogs 1 and 2 had examinations and investigations performed. Whole genome sequencing of Dog 1 and further genetic analyses in the family were performed. A cohort of 115 Eurasier controls was genotyped for specific variants.

RESULTS

Episodes were characterized by generalized ataxia, as well as a hypermetric thoracic limb gait, dystonia, and irregular flexion and extension movements of the thoracic limbs. Magnetic resonance imaging of the brain in Dogs 1 and 2 identified symmetrical, bilateral T2 and fluid attenuated inversion recovery hyperintense, T1 hypo to isointense, nonenhancing lesions of the caudate nucleus, lateral and medial geniculate nuclei, thalamus, hippocampus, rostral colliculus and mild generalized brain atrophy. Genetic analyses identified a homozygous mitochondrial trans-2-enoyl-CoA reductase (MECR) missense variant in all 3 dogs, and a homozygous autophagy-related gene 4D (ATG4D) missense variant in Dogs 1 and 2.

CONCLUSIONS AND CLINICAL IMPORTANCE

We describe a presumed hereditary and progressive polioencephalopathy in a family of Eurasier dogs. Further research is needed to establish the role of the MECR gene in dogs and the pathogenic effects of the detected variants.

Dystonic head tremor in paroxysmal dyskinesia in 17 dogs (2021-2023)

BACKGROUND

Dystonia is a common component of the movement disorder paroxysmal dyskinesia (PD) in dogs. However, the incidence of dystonic head tremor (DHT) in these dogs has not previously been evaluated.

METHODS

The medical records of dogs presenting with PD between 2021 and 2023 were retrospectively reviewed, and those with available video footage and the presence of a head tremor were selected for further analysis.

RESULTS

Seventeen of the 39 (43.6%) dogs diagnosed with PD that had video footage available manifested DHT. Poodle or Poodle-cross was the most commonly affected breed (7/17). DHTs were described as fine irregular head tremors accompanied by cervical dystonia (17/17), truncal (11/17) or head (10/17) sway, shifting limb (10/17) or single limb (6/17) dystonia, freezing (8/17), ataxia (6/17), ptyalism (5/17), falling (5/17), kyphosis (4/17) and prayer posture (4/17). Neurological examination and advanced imaging, when available, were within normal limits.

LIMITATIONS

The limitations of the study include its retrospective nature, the lack of video recordings for all PD patients and the lack of electrophysiological evaluation of tremors and electroencephalography.

CONCLUSIONS

DHT exists in dogs with PD; it has characteristic features, and it should be considered in differential diagnoses for dogs with head tremors.

Trismus due to myotonia associated with hyperadrenocorticism in a dog

We present the report of trismus due to hyperadrenocorticism-associated myotonia diagnosed by electromyography in a dog. An intact female Miniature Dachshund, 13 years and 9 months old, presented with stiff gait and trismus as well as polyuria and polydipsia. Abdominal ultrasonography showed enlarged adrenal glands. An adrenocorticotropic hormone stimulation test revealed an exaggerated response. Based on these findings, this case was diagnosed with hyperadrenocorticism. Electromyography revealed myotonic discharge in the temporalis muscle and limbs. Therefore, trismus was considered to be caused by hyperadrenocorticism-associated myotonia, and the case was treated with oral trilostane (1.3 mg/kg, once daily). During the 4-month follow-up period, despite the partial improvement in stiff gait, trismus did not recover. Long-term data on more cases are warranted to assess the prognosis and clinical characteristics of trismus due to hyperadrenocorticism-associated myotonia.

Very-Low-Frequency Spike-Wave Complex Partial Motor Seizure Mimicking Canine Idiopathic Head Tremor Syndrome in a Dog

Canine idiopathic head tremor syndrome (CIHTS) represents a benign condition characterized by episodic, uncontrolled movement of the head. Even though the condition might be an expression of a partial motor epilepsy, to date, there is a limited number of studies describing the electroencephalographic features. In this report, we describe the case of a dog diagnosed with partial motor epilepsy resembling CIHTS symptomatology, a new slow spike-wave complex pattern similar to that of Lennox-Gastaut syndrome in humans identified on electroencephalographic examination. We also studied the efficacy of phenobarbitone therapy over a period of two years.

Investigation of the presence of specific neural antibodies in dogs with epilepsy or dyskinesia using murine and human assays

BACKGROUND

Autoimmune mechanisms represent a novel category for causes of seizures and epilepsies in humans, and LGI1-antibody associated limbic encephalitis occurs in cats.

HYPOTHESIS/OBJECTIVES

To investigate the presence of neural antibodies in dogs with epilepsy or dyskinesia of unknown cause using human and murine assays modified for use in dogs.

ANIMALS

Fifty-eight dogs with epilepsy of unknown cause or suspected dyskinesia and 57 control dogs.

METHODS

Serum and CSF samples were collected prospectively as part of the diagnostic work-up. Clinical data including onset and seizure/episode type were retrieved from the medical records. Screening for neural antibodies was done with cell-based assays transfected with human genes for typical autoimmune encephalitis antigens and tissue-based immunofluorescence assays on mouse hippocampus slices in serum and CSF samples from affected dogs and controls. The commercial human und murine assays were modified with canine-specific secondary antibody. Positive controls were from human samples.

RESULTS

The commercial assays used in this study did not provide unequivocal evidence for presence of neural antibodies in dogs including one dog with histopathologically proven limbic encephalitis. Low titer IgLON5 antibodies were present in serum from one dog from the epilepsy/dyskinesia group and in one dog from the control group.

CONCLUSION AND CLINICAL IMPORTANCE

Specific neural antibodies were not detected using mouse and human target antigens in dogs with epilepsy and dyskinesia of unknown origin. These findings emphasize the need for canine-specific assays and the importance of control groups.

A TNR Frameshift Variant in Weimaraner Dogs with an Exercise-Induced Paroxysmal Movement Disorder

BACKGROUND

Some paroxysmal movement disorders remain without an identified genetic cause.

OBJECTIVES

The aim was to identify the causal genetic variant for a paroxysmal dystonia-ataxia syndrome in Weimaraner dogs.

METHODS

Clinical and diagnostic investigations were performed. Whole genome sequencing of one affected dog was used to identify private homozygous variants against 921 control genomes.

RESULTS

Four Weimaraners were presented for episodes of abnormal gait. Results of examinations and diagnostic investigations were unremarkable. Whole genome sequencing revealed a private frameshift variant in the TNR (tenascin-R) gene in an affected dog, XM_038542431.1:c.831dupC, which is predicted to truncate more than 75% of the open read frame. Genotypes in a cohort of 4 affected and 70 unaffected Weimaraners showed perfect association with the disease phenotype.

CONCLUSIONS

We report the association of a TNR variant with a paroxysmal dystonia-ataxia syndrome in Weimaraners. It might be relevant to include sequencing of this gene in diagnosing humans with unexplained paroxysmal movement disorders. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Long-term nutritional management of an obese German Spitz with paroxysmal dyskinesia, calcium oxalate urolithiasis, and suspected pancreatitis—A case report

Background

To our knowledge, this is the first description of long-term nutritional management in a dog with paroxysmal dyskinesia.

Case summary

An obese 9-year-old, male entire, German Spitz was presented for dietary management after being diagnosed with calcium oxalate urolithiasis and suspected pancreatitis. Since he was seven years old, the dog has had a history of neurological signs, which were thought to be epileptic seizures. He was treated with phenobarbital and potassium bromide and was clinically controlled. For his nutritional advice, aiming to minimize one of the most important risk factors for the diseases, a weight loss program was started and successfully executed. However, 10 months later, the dog restarted presenting neurological episodes at a high frequency (3x/week). Based on videos and the characteristics of the neurological signs, the dog was diagnosed with paroxysmal dyskinesia. To investigate the role of gluten intake on this patient's neurological signs, a dietary trial with a commercial hypoallergenic diet (gluten-free; hydrolyzed protein) was followed. During the 3 months of the dietary trial, four neurologic episodes related to food indiscretion occurred. Upon the decrease in neurological episodes, the anti-seizure drugs were slowly discontinued. During this period, the dog presented only two neurologic episodes that were related to the days that the anti-seizure drugs were decreased. For 4 months the dog remained episode-free. However, a change in the dog's diet to another gluten-free diet (higher fat) led the dog to vomit and experience another neurologic episode. Once the dog was back to the previous gluten-free diet, it clinically improved, and no other clinical signs were reported by the client during the next 5 months.

Conclusion

Although a relationship between gluten and paroxysmal dyskinesia cannot be confirmed, the dog's improvement after the nutritional management and the removal of the anti-seizure therapy is supportive of dietary association.

Gluten serological testing in various dog breeds with paroxysmal dyskinesia

Background

Paroxysmal gluten-sensitive dyskinesia is a subtype of movement disorder classified as canine paroxysmal dyskinesia (cPD), which until now has only been described in Border Terriers (BT).

Objectives

Our aim was to report cPD with positive gluten serology in dog breeds other than BT.

Animals

Thirty-one client-owned dogs with suspected cPD were examined in this study.

Methods

The hospital records of the dogs where the serum was tested for modified gliadin peptide immunoglobulin G (gliadin IgG) and tissue transglutaminase-2 immunoglobulin A (transglutaminase-2 IgA) were studied. A total of 31 dogs were presented to the clinic with cPD. A work-up consistent with Tier 1 or Tier 2 confidence levels for canine epilepsy was undertaken in all dogs. The dogs' diets and episode descriptions or videos in 16/31 cases were additionally studied. A follow-up was held to inquire about the dogs' wellbeing and response to the diet changes.

Results

Fourteen of the 31 dogs tested positive for gluten sensitivity with either gliadin IgG or transglutaminase-2 IgA or both ratios elevated. In seven dogs, serology was classified as questionable with gliadin IgG or transglutaminase ratios mildly elevated. Ten dogs tested negative. According to the owners' reports, five of the dogs that tested positive had no more episodes after changing to a strictly gluten-free diet, with one of the dogs relapsing twice after being fed treats containing gluten. Three dogs had a reduction in episode frequency of >50%, and two dogs had shorter and less intense episodes.

Conclusion

A considerable subset of dog breeds presented for presumed cPD showed laboratory signs of gluten sensitivity and responded to a gluten-free diet.

The Potential of Bemegride as an Activation Agent in Electroencephalography in Dogs

The present study investigated the potential of bemegride as a pharmacological activation agent that elicits epileptiform discharges (EDs) in interictal electroencephalogram (EEG) recordings in dogs. Four laboratory dogs with idiopathic epilepsy and four without epilepsy were included. The dogs were anesthetized using sevoflurane during EEG recordings. Bemegride was administered intravenously and repeatedly until EDs were enhanced or induced, or until the maximum dose (20 mg/kg) had been administered. Bemegride activated EDs in all dogs with epilepsy. These EDs predominantly occurred in each dog's spontaneous irritative zones, which were identified without the administration of bemegride. EDs occurred after the administration of bemegride in 50% of dogs without epilepsy. The dose required for activation was significantly lower in dogs with epilepsy (median; 7.3 mg/kg) than in those without (median; 19.7 mg/kg) (p = 0.0294). The only suspected adverse effect associated with the administration of bemegride was vomiting in two dogs after awakening from anesthesia. There were no other adverse effects, including seizures. The present results demonstrated the potential of bemegride as a safe and effective pharmacological activation agent of EDs in anesthetized dogs with epilepsy and provided more options for the diagnosis and therapeutic planning of epilepsy, including presurgical evaluations, in dogs.

Novel subscalp and intracranial devices to wirelessly record and analyze continuous EEG in unsedated, behaving dogs in their natural environments: A new paradigm in canine epilepsy research

Epilepsy is characterized by unprovoked, recurrent seizures and is a common neurologic disorder in dogs and humans. Roughly 1/3 of canines and humans with epilepsy prove to be drug-resistant and continue to have sporadic seizures despite taking daily anti-seizure medications. The optimization of pharmacologic therapy is often limited by inaccurate seizure diaries and medication side effects. Electroencephalography (EEG) has long been a cornerstone of diagnosis and classification in human epilepsy, but because of several technical challenges has played a smaller clinical role in canine epilepsy. The interictal (between seizures) and ictal (seizure) EEG recorded from the epileptic mammalian brain shows characteristic electrophysiologic biomarkers that are very useful for clinical management. A fundamental engineering gap for both humans and canines with epilepsy has been the challenge of obtaining continuous long-term EEG in the patients' natural environment. We are now on the cusp of a revolution where continuous long-term EEG from behaving canines and humans will be available to guide clinicians in the diagnosis and optimal treatment of their patients. Here we review some of the devices that have recently emerged for obtaining long-term EEG in ambulatory subjects living in their natural environments.

Dystonia in veterinary neurology

Dystonia is a clinical sign and main feature of many movement disorders in humans as well as veterinary species. It is characterized by sustained or intermittent involuntary muscle contractions causing abnormal (often repetitive) movements, postures, or both. This review discusses the terminology and definition of dystonia, its phenomenology, and its pathophysiology, and provides considerations regarding the diagnosis and treatment of dystonia in dogs and cats. In addition, currently recognized or reported disorders in dogs and cats in which dystonia is a particular or main feature are discussed and comparisons are made between disorders featuring dystonia in humans and animals. We suggest that when describing the phenomenology of dogs and cats with dystonia, if possible the following should be included: activity being performed at onset (e.g., resting or running or exercise-induced), body distribution, duration, responsiveness (subjective), severity, temporal pattern (i.e., paroxysmal or persistent, severity at onset and at later stages), presence or absence of autonomic signs (e.g., salivation), presence or absence of preceding signs (e.g., restlessness), presence or absence of signs after dystonia subsides (e.g., sleepiness), coexistence of other movement disorders, any other neurological manifestations, and possible links to administered medications, intoxications or other associated factors. We also suggest that dystonia be classified based on its etiology as either structural genetic, suspected genetic, reactive, or unknown.

Movement Disorders and Cerebellar Abiotrophy

Movement disorders are defined as involuntary movements that are not due to a painful stimulus or associated with changes in consciousness or proprioception. Diagnosis involves ruling out any lameness and neurologic disease and characterizing the gait during walking backward and forward and trotting. Shivers causes abnormal hindlimb hypertonicity during walking backward and, when advanced, a few strides walking forward. Stringhalt causes consistent hyperflexion during walking forward and trotting and variable difficulty when walking backward. Classification and potential causes are discussed as well as other enigmatic movement disorders in horses are presented. Cerebellar abiotrophy is reviewed.

Dogs as a Natural Animal Model of Epilepsy

Epilepsy is a common neurological disease in both humans and domestic dogs, making dogs an ideal translational model of epilepsy. In both species, epilepsy is a complex brain disease characterized by an enduring predisposition to generate spontaneous recurrent epileptic seizures. Furthermore, as in humans, status epilepticus is one of the more common neurological emergencies in dogs with epilepsy. In both species, epilepsy is not a single disease but a group of disorders characterized by a broad array of clinical signs, age of onset, and underlying causes. Brain imaging suggests that the limbic system, including the hippocampus and cingulate gyrus, is often affected in canine epilepsy, which could explain the high incidence of comorbid behavioral problems such as anxiety and cognitive alterations. Resistance to antiseizure medications is a significant problem in both canine and human epilepsy, so dogs can be used to study mechanisms of drug resistance and develop novel therapeutic strategies to benefit both species. Importantly, dogs are large enough to accommodate intracranial EEG and responsive neurostimulation devices designed for humans. Studies in epileptic dogs with such devices have reported ictal and interictal events that are remarkably similar to those occurring in human epilepsy. Continuous (24/7) EEG recordings in a select group of epileptic dogs for >1 year have provided a rich dataset of unprecedented length for studying seizure periodicities and developing new methods for seizure forecasting. The data presented in this review substantiate that canine epilepsy is an excellent translational model for several facets of epilepsy research. Furthermore, several techniques of inducing seizures in laboratory dogs are discussed as related to therapeutic advances. Importantly, the development of vagus nerve stimulation as a novel therapy for drug-resistant epilepsy in people was based on a series of studies in dogs with induced seizures. Dogs with naturally occurring or induced seizures provide excellent large-animal models to bridge the translational gap between rodents and humans in the development of novel therapies. Furthermore, because the dog is not only a preclinical species for human medicine but also a potential patient and pet, research on this species serves both veterinary and human medicine.

Phenotypic characterisation of paroxysmal dyskinesia in Sphynx cats

OBJECTIVES

The aim of this study was to identify the phenotypic features of a paroxysmal dyskinesia observed in Sphynx cats.

METHODS

The owners of affected Sphynx cats were invited to provide video footage of abnormal episodes for review. Those that demonstrated episodes consistent with paroxysmal dyskinesia were then invited to complete an online questionnaire designed to allow further characterisation.

RESULTS

Ten Sphynx cats were included in the study. All affected cats were <4 years of age at the onset of the episodes (range 0.5-4.0). The episodes had a duration of <5 mins in 9/10 cats (range 0.5-10), while episode frequency was variable between and within individual cats. The episodes were characterised by impaired ambulation due to muscle hypertonicity, most commonly affecting the hips and pelvic limbs (9/10) and shoulders and thoracic limbs (8/10). The head and neck (6/10), tail (5/10), and back and abdomen (3/10) were also involved in some cats. Sudden movement, excitement and stress were identified as possible triggers for the episodes in three cats. Therapeutic intervention was not attempted in 7/10 cases, although two cats were reported to become free of the episodes while receiving acetazolamide. The two cats that were followed beyond 2 years from onset entered spontaneous remission. None of the owners believed that the abnormal episodes had affected the quality of life of their cat.

CONCLUSIONS AND RELEVANCE

The phenotype of paroxysmal dyskinesia in Sphynx cats presented in this study appears to share similarities with paroxysmal kinesigenic dyskinesia described in human classification systems. Some cats appear to achieve episode freedom spontaneously. Subsequent research should focus on evaluating response to treatment and determining an underlying genetic cause.

Shivering and Stringhalt in horses

Pelvic limb movement disorders unrelated to lameness or proprioceptive ataxia have been described in horses for centuries. The two best described are Shivering and Stringhalt. Shivering is unique in that it is primarily apparent when horses are asked to walk backward, without affecting forward gaits until quite advanced. Horses exhibit abduction and either hyperflexion or marked hyperextension of one or both pelvic limbs when walking backward, resulting in a pause at the peak of the stride cycle and reluctance to move backward. Generally, Stringhalt differs from Shivering in that it produces consistent hyperflexion without abduction in forward gaits including walk and trot. This review will focus on the two most common pelvic limb movement disorders, Shivering and Stringhalt, their clinical presentation, differential diagnosis, etiopathology, and treatment.

Myoclonus in older Cavalier King Charles Spaniels

Background

Myoclonus is observed in older Cavalier King Charles Spaniels (CKCS) but a full description is lacking.

Objectives

The presence, age of onset, characteristics and treatment of myoclonic episodes were retrospectively evaluated in a cohort of CKCS which presented to 1 board‐certified neurologist. Clinical data, imaging studies, presence of seizures and their management, as well as other comorbidities were noted.

Animals

Thirty‐nine CKCS that were presented to 2 institutions between 2001 and 2018 with signs consistent with myoclonus. Clinical examination, blood sampling, advanced diagnostic imaging, cerebrospinal fluid analysis, and record keeping of other comorbidities was performed.

Methods

This is a retrospective case series, describing the presence of myoclonus in CKCS.

Results

Clinical signs reported were spontaneous in onset, lasted a few seconds and consisted of rapid blinking with head nodding and variable extension down the thoracic limbs. Myoclonus occasionally led to stumbling of the thoracic limbs or collapse. Mean age of onset was 8.38 years (SD ±1.96). Thirteen of 39 dogs with myoclonus had paroxysmal events, such as generalized seizures (9/13).

Conclusions and Clinical Importance

Myoclonus occurs in middle‐aged to older CKCS and seems to be another epiphenomena of this breed. A link to epilepsy might be present.

Clinical characterisation of a novel paroxysmal dyskinesia in Welsh terrier dogs

Breed specific paroxysmal dyskinesias are increasingly recognised in veterinary medicine. We aimed to characterise the phenomenology, clinical course and prevalence of a previously unreported paroxysmal dyskinesia in the Welsh terrier breed. Clinical records of five Welsh terriers with paroxysmal episodes were reviewed. Additionally, owners of Welsh terriers were invited to complete a questionnaire with the aim of characterising paroxysmal episodes in the wider breed population. Clinical examinations (n = 5) and diagnostic investigations (n = 2) of affected Welsh terriers were within normal limits, apart from mild-moderate ventriculomegaly on cranial magnetic resonance imaging (n = 3). The survey of Welsh terrier owners revealed episodes consistent with a paroxysmal dyskinesia in 41 (22.8%) of 177 respondents. Median age of onset was 59 months. Episodes were predominantly characterised by sustained hypertonicity with periods of limb flexion, abnormal head and body posture, with preserved consciousness. Episode duration ranged from 30 s to 30 min (median, 3 min 30 s), with frequency varying widely between dogs. Affected dogs demonstrated a stable to improving clinical course in most cases. This study investigated a previously unreported paroxysmal dyskinesia in Welsh terriers. Similar clinical signs within the breed were potentially consistent with an inherited cause, worthy of further investigation.

International veterinary canine dyskinesia task force ECVN consensus statement: Terminology and classification

Movement disorders are a heterogeneous group of clinical syndromes in humans and animals characterized by involuntary movements without changes in consciousness. Canine movement disorders broadly include tremors, peripheral nerve hyperexcitability disorders, paroxysmal dyskinesia, and dystonia. Of these, canine paroxysmal dyskinesias remain one of the more difficult to identify and characterize in dogs. Canine paroxysmal dyskinesias include an array of movement disorders in which there is a recurrent episode of abnormal, involuntary, movement. In this consensus statement, we recommend standard terminology for describing the various movement disorders with an emphasis on paroxysmal dyskinesia, as well as a preliminary classification and clinical approach to reporting cases. In the clinical approach to movement disorders, we recommend categorizing movements into hyperkinetic vs hypokinetic, paroxysmal vs persistent, exercise‐induced vs not related to exercise, using a detailed description of movements using the recommended terminology presented here, differentiating movement disorders vs other differential diagnoses, and then finally, determining whether the paroxysmal dyskinesia is due to either inherited or acquired etiologies. This consensus statement represents a starting point for consistent reporting of clinical descriptions and terminology associated with canine movement disorders, with additional focus on paroxysmal dyskinesia. With consistent reporting and identification of additional genetic mutations responsible for these disorders, our understanding of the phenotype, genotype, and pathophysiology will continue to develop and inform further modification of these recommendations.